Apparatus for rifling gun barrels



Jan. 20, 1931. J. L. HATCHER APPARATUS FOR RIFLING GUN BARRELS FiledJuly 25, 1927 Patented Jan. 20, 1931 UNITED STATES JAMES L. HATGHER, OFWINCHESTER, VIRGINIA.

APPARATUS FOR RIFLING GUN BARRELS Application filed July 25, 1927.Serial mi. 208,813.

(GRANTED UNDER THE ACT OF MARCH 3, 1883, AS AHENI JED APRIL 30, 1928;370 0. G. 757) The invention described herein. may be manufactured andused by or for the Government for governmental purposes without thepayment to me of any royalty thereon.

Thisinvention relates to an apparatus for rifling gun barrels and thelike.

The recent development of a type of iron and steel alloy generallydesignated as stainless or unstainable has resulted in proposals toemploy it in gun barrels because its physical properties of highresistance to wear and erosion are admirably suited to this purpose. 1

This type of steel however possesses certain mechanical properties whichare exhibited in its capacity for flowin and work hardening and becauseof this di culties are presented in rifiing a gun barrel by thecustomary machining operation.

end of the cutting tool produces a grinding rather than a cutting actionthe foregoing mechanical properties are reflected in a tendency of themetal to push ahead and bank up in front of the tool and also in atendency to form a hardened skin which will resist cutting. If thistrouble is to be avoided'by the exercise of every possible precautionthe cutting operation would be extremely slow due to the hardness of.the metal and it would be so necessary to frequently interrupt the workfor the purpose of tempering the metal.

Accordingly it is proposed in the present' invention to form the riflinby a cold Workv operation which will not on y permit simul- 23 tane'ousformation ofthe riflin in a number of barrels but will serve to raisethe elastic limit of the metal. The apparatus employed in carrying outtheinvention is characterized by a novel arrangement designed to hold a-1 tool bar against bending as it is forced into the barrel.

A practical embodiment of the invention is illustrated in theaccompanying drawing, wherein:

tool holder Fig. 2 is an end view thereof; I

Figs. 3 and 4 are detail views; respectively in side elevation and planof the rifling mem- Since the foremost Referring to the drawings bynumerals of reference. I The apparatus employed in conducting thecoldwork operation includes a hollow supportor holder 5 formed with aplurality of equally spaced parallel guide-Ways 6 in which the. bars 7carrying the rifling members 8 are reciprocally mounted.

The guide-ways are circular in form corresponding in diameter to thebore of the gun barrel and all of them are provided with'a slot 9opening into the bore of the support and extending substantiallythroughout the length of thesupport in order to provide for movement ofa ram 10 Whose extremities fit in the guide-ways.

The rifling members 8 are revolubly mounted on their bars and'are eachprovided with' spiral ribs 11. As these members are forced' through thebore of the barrel the ribs ng substantially throughout its length, barsmounted in the guide ways, rifling members revolvably carried on one endof the bars and a ram mounted for sliding movement in the guide-ways andengageable with the other end of the bars.

JAMES L. HATCHER.

Fig. 1 is a view in side elevation of the

